Friday\'s cyber attack hit 200,000 victims in at least 150 countries and that number could grow when people return to work on Monday, the head of the European Union\'s police agency said on Sunday, reports Reuters.

Cyber security experts say the spread of the virus dubbed WannaCry - "ransomware" which locked up computers in car factories, hospitals, shops and schools in several countries - has slowed, but that any respite might be brief.

Europol Director Rob Wainwright told ITV\'s Peston on Sunday program the attack was unique in that the ransomware was used in combination with "a worm functionality" so the infection spread automatically.

"The global reach is unprecedented. The latest count is over 200,000 victims in at least 150 countries, and those victims, many of those will be businesses, including large corporations," he said.

"At the moment, we are in the face of an escalating threat. The numbers are going up; I am worried about how the numbers will continue to grow when people go to work and turn (on) their machines on Monday morning."

He said Europol and other agencies did not yet know who was behind the attack but "normally it is criminally minded and that is our first working theory for obvious reasons".